Diaphragm for sound receiving, reproducing, amplifying, and transmitting instruments



Aug. 23, 1932. -r 1,873,335

DIAPHRAGI FOR SOUND RECEIVING, REPRODUCING,

ANPLIFYING AND TRANSMITTING INSTRUMENTS Filed Sept. 10. 1930 INVENTo HANS. SCHMIDT.

ATTORNEY.

Patented Aug. 23, 1932 UNITED STATES HANS SCHMIDT, OF JENA, GERMANY DIAPHRAGM FOR SOUND RECEIVING, BEPRODUCING, AMPLIFYING, AND TRANSMIT- TING INSTRUMENTS Application filed September 10, 1980, Serial No. 481,031, and in Germany October 15, 1929.

Diaphragms used in sound receiving, reproducing amplilying and transmitting apparatus, which I will refer to generally as acoustic diaphragms, constructed solely of paper or some such material, have the defect that the vibration thereof does not proceed solely in the direction of the impulse producing it, but also in transverse directions, and this produces impure or distorted acoustic effects.

According to my invention, which relates to coned diaphragms, this defect is overcome by constructing the diaphragm of a very thin sheet, e. g. of paper, with strips stuck thereto side by side, the strips consisting of fibrous vegetable material of a kind in which the fibres enclose pith, and the fibres extending longitudinally of the strips, from the part where the impulse is applied substantially in the direction in which the vibration is to be propagated. Plant stalks, e. g. straw stalks, are suitable for this purpose, the same being flattened by suitable means. I may for example slit the stalks, heat them by means of steam, and flatten them by pressing, ironing or other convenient means.

An example is illustrated in the accompanying drawing in which Fig. 1 is a plan view of the blank partially formed.

Fig. 2 is a side elevation of the diaphragm.

The diaphragm shown comprises a thin sheet a of paper of coned shape, truncated so that there is a hole b at the apex. To this sheet are stuck sector shaped strips 0 of flattened straw.

Straw is a very light material, with a high degree of internal damping, due largely to the loose textured pith and its dense fibrous structure enables it to transmit even minute mechanical vibrations in the direction in which it is layed.

The invention is applicable to acoustic diaphragms for all purposes, including dia-- phragms for loud-speakers. The soundreproduction obtained is exceedingly true, over a very wide range of notes, including the over-tones.

WVhat I claim as my invention and desire to secure by Letters Patent of the United States 1s:

1. An acoustic diaphragm consisting of a thin sheet and flattened straw-stalks stuck side by side to saidshcet, the fibres of the stalks extending substantially in the direction in which the vibration is to be transmitted.

' 2. An acoustic diaphragm consisting of a thin sheet and strips of fibrous material stuck" side by side to said sheet, the fibres extending substantially in the direction in which the vibration. is to be transmitted, said strips cons sting of straw stalks slit open, steamed and flattened.

3. An acoustic diaphragm consisting of a thin'sheet of conical shape, and strips stuck side by side to said sheet, the strips consisting of fibrous vegetable material and having an inside layer of pith, and extending in the direction in which the vibration is to be transmitted.

4. An acoustic diaphragm consisting of a thin sheet of conical shape and strips stuck side by side to said sheet, said strips consist ing of fibrous vegetable material composed of a layer of fibres and a layer of pith upon said fibres, and said fibres extending in the direction in which the vibration is to be transmitted.

5. An acoustic diaphragm consisting of a thin sheet of conical shape and sector shaped strips stuck side by side to said sheet, extending from the center thereof to the circumference, said strips consisting of fibrous vegetable material composed of a. layer of fibres and a layer of pith upon said fibres.

' HANS SCHMIDT. 

